Power converting apparatus and power generating apparatus

ABSTRACT

AC module makers must prepare two types of AC modules for the 100-V and 200-V outputs only for domestic supply. For foreign countries, the makers must manufacture AC modules compatible with more system voltages. To solve these problems, the control circuit of an AC module controls the operation of an inverter circuit and/or the transformation ratio of a transforming circuit, and ON/OFF-controls a switch on the basis of the system voltage and connection state of an electric power system.

FIELD OF THE INVENTION

[0001] The present invention relates to a power converting apparatus andpower generating apparatus and, more particularly, to a power convertingapparatus such as an inverter connectable to an electric power systemand a power generating apparatus for converting a power outputted from adirect current power supply unit such as a solar battery or storagebattery into alternating current power by a power converting apparatusand supplying the alternating current power to a load or electric powersystem.

BACKGROUND OF THE INVENTION

[0002] In recent years, many solar power generation apparatuses forconverting direct current power generated by a solar battery intoalternating current power by an inverter and supplying the alternatingcurrent power to a load in a house (to be simply referred to as a “load”hereinafter) and/or a commercial electric power system (to be simplyreferred to as a “system” hereinafter) are installed to deal withenvironmental problems.

[0003] These solar power generation apparatuses have also received agreat deal of attention as emergency power supplies to be used in theevent of disasters such as an earthquake. Even when power outage occursdue to an earthquake, system failure, or maintenance, many recent solarpower generation apparatuses can be disconnected from systems and supplya power to loads by isolated operation.

[0004] AC modules have also received a great deal of attention as small-or medium-scale solar power generation apparatuses or emergency powersupplies, which allow a single solar battery module to outputalternating current power by attaching, to, e.g., the lower surface of asolar battery module, a small inverter called a MIC (Module IntegratedConverter) for converting direct current power generated by a solarbattery into alternating current power.

[0005] As disclosed in Japanese Patent Laid-Open No. 10-14111, an ACmodule is connected to the neutral line and one power line of asingle-phase three-wire unit and then connected to a system. In anemergency, a solar power generation apparatus using an AC module usesalternating current power obtained by converting direct current powerstored in a storage battery by an emergency inverter.

[0006] An AC module is connected to a system in a building through apanel board or the like. In Japan, the voltage of a system in a buildingis 100 V or 200 V, and an AC module must select a 100-V output or 200-Voutput in accordance with the connection. Hence, AC module makers mustprepare two types of modules for the 100-V and 200-V outputs fordomestic supply. For foreign countries, the makers must manufacture ACmodules compatible with more system voltages.

[0007] If the output voltage changes in switching from interconnectedoperation to isolated operation, an easier switching method is requiredfor an emergency power supply. Especially in disasters or the like, anAC module need be carried to an arbitrary position together with a loadand easily output a desired voltage.

SUMMARY OF THE INVENTION

[0008] The present invention has been made to solve the above-describedproblems individually or altogether, and has as its object to make apower converting apparatus easily cope with many types of systemvoltages.

[0009] It is another object of the present invention to set the outputvoltage of a power converting apparatus in accordance with a systemvoltage.

[0010] It is still another object of the present invention to easilymove and install a power converting apparatus in an emergency.

[0011] In order to achieve the above objects, according to a preferredaspect of the present invention, a power converting apparatus which isconnected to an electric power system, the apparatus comprising: aconverting circuit, arranged to convert direct current power toalternating current power; a transforming circuit, arranged to transformvoltage outputted from the converting circuit; a switch, arranged tomake/break connection between the transforming circuit and the electricpower system; and a controller, arranged to control operation of theconverting circuit and transforming circuit, and connection of theswitch based on a line voltage of the electric power system and/or aconnection state between the apparatus and the electric power system isdisclosed.

[0012] In addition, a power converting apparatus which is connected toan electric power system, the apparatus comprising: a convertingcircuit, arranged to convert direct current power to alternating currentpower; a transforming circuit, arranged to transform voltage outputtedfrom the converting circuit; a switch, arranged to make/break connectionbetween the transforming circuit and the electric power system; and acontroller, arranged to control operation of the converting circuitand/or transforming circuit, and control connection of the switch basedon a type of connector which is used to connection between the apparatusand the electric power system is disclosed.

[0013] Also, a power converting apparatus which is connected to anelectric power system, the apparatus comprising: a converting circuit,arranged to convert direct current power to alternating current power; aswitch, arranged to make/break connection between the converting circuitand the electric power system; and a controller, arranged to controloperation of the converting circuit and connection of switch based on atype of connector which is used to connection between the apparatus andthe electric power system is disclosed.

[0014] It is still another object to easily and reliably switch theoutput voltage of a power converting apparatus.

[0015] It is still another object to easily and reliably switch betweeninterconnected operation and isolated operation.

[0016] In order to achieve the above objects, according to anotherpreferred aspect of the present invention, a power converting apparatusfor converting electric power comprising: a booster circuit, arranged toboost voltage of direct current power inputted from a direct currentpower supply; an inverter circuit, arranged to convert the directcurrent power, which is inputted from the booster circuit, toalternating current power; an output port, arranged to output thealternating power supplied from the inverter circuit; and a controller,arranged to control operation of the booster and inverter circuits basedon a type of plug unit connected to the output port is disclosed.

[0017] In addition, a power converting apparatus for converting electricpower comprising: a booster circuit, arranged to boost voltage of directcurrent power inputted from a direct current power supply; an invertercircuit, arranged to convert the direct current power, which is inputtedfrom the booster circuit, to alternating current power; a first outputport, arranged to output the alternating power supplied from theinverter circuit through a first switch; a second output port, arrangedto output the alternating power supplied from the inverter circuitthrough a second switch; and a controller, arranged to control operationof the booster and inverter circuits, wherein the controller makes thefirst switch and breaks the second switch when the apparatus is operatedand connected to an electric power system, and breaks the first switchand makes the second switch when the apparatus is operated and noconnected to the electric power system, and the controller controls theoperation of the booster and inverter circuits based on a connectionstate of the first or second output port is disclosed.

[0018] Other features and advantages of the present invention will beapparent from the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a view showing a boosting chopper circuit;

[0020]FIG. 2 is a block diagram showing the arrangement of a controlcircuit;

[0021]FIG. 3 is a block diagram showing the arrangement of a solar powergeneration apparatus of the first example;

[0022]FIG. 4 is a block diagram showing the detailed arrangement of atransforming circuit of the first example;

[0023]FIG. 5 is a block diagram showing the arrangement of a solar powergeneration apparatus of the second example;

[0024]FIG. 6 is a block diagram showing the detailed arrangement of atransforming circuit of the second example;

[0025]FIG. 7 is a view for explaining the output connector (receptacle)of an output terminal of an inverter of the third example;

[0026]FIG. 8 is a block diagram showing the arrangement of a solar powergeneration apparatus of the third example;

[0027]FIG. 9 is a block diagram showing the arrangement of a solar powergeneration apparatus of the fourth example;

[0028]FIG. 10 is a block diagram showing the arrangement of a solarpower generation apparatus of the fifth example;

[0029]FIG. 11 is a block diagram showing the arrangement of a solarpower generation apparatus of the sixth example;

[0030]FIG. 12 is a view showing the outer appearance of an AC moduleusing an inverter of the seventh example;

[0031]FIG. 13 is a view for explaining a plug unit;

[0032]FIG. 14 is a view showing the arrangement of an output section;

[0033]FIG. 15 is a view showing another arrangement of the outputsection; and

[0034]FIG. 16 is a view showing still another arrangement of the outputsection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] A solar power generation apparatus according to an embodiment ofthe present invention will be described below in detail with referenceto the accompanying drawings.

[0036] First Embodiment

[0037] [Direct Current Power Supply]

[0038] Any kind of direct current power supply for generating directcurrent power can be used, including a solar battery, fuel cell, storagebattery, thermocouple, and plasma power generating unit.

[0039] A solar battery used in this embodiment is not particularlylimited. As a photovoltaic element made of a silicon semiconductor, asingle-crystal silicon solar battery, polysilicon solar battery,amorphous silicon solar battery, or the like can be used. As aphotovoltaic element made of a compound semiconductor, a III-V compoundsolar battery, II-VI compound solar battery, I-III-VI compound solarbattery, or the like can be used.

[0040] A desired number of solar batteries are connected in series andparallel, inserted between a surface protecting member such as a glassplate or weathering-resistance film and a lower surface reinforcingmember such as a moistureproof protective sheet or steel plate, andfixed by a filler, thereby forming a solar battery module.

[0041] A solar battery module often has an output cable structure inwhich a terminal box for extracting power or an output cable having awaterproof connector at its distal end is attached to thenon-light-receiving surface. A plurality of solar battery modules areconnected by connecting terminal boxes using output cables or connectingwaterproof connectors to each other, thereby constructing a solarbattery array.

[0042] This embodiment can also be applied to an AC module formed byattaching an inverter for converting direct current power outputted froma solar battery module into alternating current power to the lowersurface of the solar battery module or electrically and/or mechanicallyconnecting the inverter to a terminal box.

[0043] Especially an AC module preferably easily switches betweeninterconnected operation and isolated operation and preferably obtains adesired output voltage in the isolated operation mode.

[0044] [Boosting Circuit]

[0045] A boosting circuit boosts the voltage of direct current poweroutputted from a direct current power supply such as a solar battery toa voltage necessary for an inverter circuit. As a boosting circuit, aboosting chopper circuit, voltage doubler rectifying circuit, series-and parallel-connected chopper circuit, or the like can be used.

[0046]FIG. 1 is a view showing a boosting chopper circuit.

[0047] When a switching element 2 is turned on/off, the sum of an inputvoltage Vi and a voltage induced in a coil 5 can be stored in acapacitor 4 through a diode 3, thereby obtaining an output voltage Vohigher than the input voltage Vi. As the switching element 2, an IGBT orMOSFET is used.

[0048] The output voltage Vo of the boosting circuit is determined inaccordance with the ratio of on/off periods (duty ratio) of a gatesignal S inputted from a control circuit 104 to the switching element 2.The control circuit 104 controls the duty ratio of the gate signal S bya target boost voltage determined on the basis of the outputvoltage/current of a solar battery, the output voltage of an inverter,or the like.

[0049] [Inverter Circuit]

[0050] As an inverter circuit, a voltage-type inverter using an IGBT orMOSFET as a switching element is preferably used. The control circuit104 supplies the gate signal to the inverter circuit to drive aplurality of switching elements, thereby obtaining desired outputvoltage and current. The inverter circuit is controlled to executecurrent control operation in a interconnected operation mode in whichthe apparatus is connected to a system and to execute voltage/frequencycontrol operation in an isolated operation mode in which the apparatusis not connected to a system. These operations and control modes areknown and disclosed in, e.g., Japanese Patent Laid-Open No. 58-69470,though they are not limited to those in this reference.

[0051] [Control Circuit]

[0052]FIG. 2 is a block diagram showing the arrangement of the controlcircuit 104.

[0053] Referring to FIG. 2, a CPU 702 controls activation/stop andoperation mode of the inverter. In the interconnected operation mode,the CPU 702 receives the output voltage and current from the solarbattery and generates a target voltage instruction value and currentinstruction value. In the isolated operation mode, when the monitoredoutput voltage of the solar battery has a predetermined value or less,the CPU outputs a gate block signal to stop the inverter. In agenerating apparatus having a storage battery, a switch is changed overto convert direct current power obtained from the storage battery intoalternating current power without stopping the inverter. In this case,the operation of the inverter is continued until the output voltage ofthe storage battery becomes a predetermined voltage or less.

[0054] A PWM waveform control section 703 receives a voltage referencevalue or current reference value and executes so-called feedback controlto make the reference value match the output voltage or current, therebygenerating a gate signal to be supplied to the switching elements of theinverter. Such a circuit is described in, e.g., Takao Hirasa, “PowerElectronics” Kyoritu Shuppan. In this embodiment, a triangular wavecomparison type PWM waveform generation circuit using a PI(proportion-integration) control system is used.

[0055] A frequency/voltage reference generator 704 is an oscillationcircuit for generating a sine wave having a constant amplitude andconstant frequency. As the frequency/voltage reference generator 704, aknown circuit such as a Wien bridge circuit can be appropriatelyselected and used. In this embodiment, a sine wave oscillator is formedusing an operational amplifier to generate a voltage reference signal.

[0056] A current reference generator 705 generates a sine wave (currentreference signal) that has an amplitude corresponding to a currentinstruction value received from the CPU 702 and a phase almost matchinga system voltage. Such a control circuit is disclosed in, e.g., JapanesePatent Laid-Open No. 58-69470, which comprises a multiplier, atransformer for receiving a system voltage, and the like. In thisembodiment, a current reference signal is generated using a multiplierand transformer.

[0057] A mode switching device 706 selectively supplies, to thefrequency/voltage reference generator 704, a current reference signal inthe interconnected operation represented by a mode switching signaloutputted from the CPU 702 or a voltage reference signal in the isolatedoperation mode. As the mode switching device 706, a relay or analogswitch can be used. In this embodiment, a small relay is used.

[0058] A switching control section 707 outputs a gate signal to theboosting circuit on the basis of the target voltage instruction valueoutputted from the CPU 702. Hence, the output voltage Vo of the boostingcircuit is controlled to the target voltage. In this embodiment, theswitching control section 707 is formed using a comparator andmultiplier.

[0059] As described above, the control circuit 104 preferably has avoltage/frequency reference used in the isolated operation mode and acurrent reference used in the interconnected operation mode and canpreferably switch between them. The control circuit 104 may beexternally operated through a communication line or communication path.The control circuit 104 itself may be arranged outside the inverter tosystematically control a plurality of inverters.

[0060] The target value of the output voltage can be set in advance inthe control circuit 104 or can be set using a dip switch or the like inaccordance with the use condition of the inverter.

[0061] [Switch]

[0062] As a switch arranged in a panel board inserted between theinverter and the output terminal of the solar power generation apparatusor between the output terminal and a system, an electromagnetic switchor breaker can be used. For an electromagnetic switch, the ON/OFFoperation is executed in accordance with, e.g., a signal inputted fromthe control circuit 104.

[0063] [Voltage and Current Detectors]

[0064] Voltage and current detectors are not particularly limited. As acurrent detector, a shunt resistor or current transformer is used. Theterminal voltage of the shunt resistor or the output voltage of thecurrent transformer is A/D-converted and inputted to the control circuit104. As a voltage detector, a transformer or resistance potentialdivider is used. The output voltage of the transformer or resistancepotential divider is A/D-converted and inputted to the control circuit104. The voltage and current detectors can be either insulated ornon-insulated from the main circuit.

FIRST EXAMPLE

[0065]FIG. 3 is a block diagram showing the arrangement of a solar powergeneration apparatus of the first example.

[0066] Referring to FIG. 3, direct current power generated by a solarbattery module 101 is converted into alternating current power by aninverter 107 having a boosting circuit 102, inverter circuit 103,control circuit 104, transforming circuit 105, switch 108, outputconnector 106, and system voltage detector 111. The output from theinverter 107 is connected to a system 110 through a panel board 109.

[0067] As the solar battery module 101, a solar battery module PV-MR140(rated power: 140 W, 19.6 V, 7.15 A) available from Mitsubishi Electricis used. Although a stand-alone solar battery module can be used, aplurality of solar battery modules may be connected to form a solarbattery array. The number of solar battery modules connected in seriesand parallel in the solar battery array is appropriately set inaccordance with the allowable input voltage of the inverter 107 or theallowable voltage or current of the wires of the direct current circuit.

[0068] The system 110 need not always be a commercial electric powersystem. It may be a non-utility alternating current power generationfacility in a factory or the like.

[0069] When the inverter 107 is connected to the system, the systemvoltage detector 111 detects the system voltage and sends a signalrepresenting the system voltage to the control circuit 104. When thesystem is not connected to the output connector 106, and the detectedsystem voltage value is almost 0, the control circuit 104 turns off theswitch 108.

[0070] When the system is connected to the output connector 106, and asystem voltage of 200 V is detected, the control circuit 104 sends asignal to a relay 201 in the transforming circuit 105 whose detailedarrangement is shown in FIG. 4 so as to connect two secondary windingsof a transformer 203 in series and then turns on the switch 108 at anappropriate timing. As a result, the inverter 107 operates in aninterconnected operation mode for outputting alternating current powerof 200 V.

[0071] On the other hand, a system voltage of 100 V is detected, thecontrol circuit 104 sends a signal to the relay 201 to connect the twosecondary windings of the transformer 203 in parallel and then turns onthe switch 108 at an appropriate timing. As a result, the inverter 107operates in an interconnected operation mode for outputting alternatingcurrent power of 100 V.

[0072] That is, since the control circuit 104 switches the setting ofthe transforming circuit 105 in accordance with the detected systemvoltage, the inverter 107 operates in the interconnected operation modefor outputting alternating current power of 200 V or 100 V in accordancewith the system voltage. Note that the control circuit 104 not onlyswitches the setting of the transforming circuit 105 in accordance withthe detected system voltage but also switches the set value of thedetection voltage of an overvoltage protecting circuit (not shown).

[0073] Although the use efficiency of the transformer becomes low, thetransformer 203 having a 100-V tap may be used to extract power fromboth ends of the secondary windings when the system voltage is 200 V orto extract power from the 100-V tap when the system voltage is 100 V.

[0074] As described above, the inverter 107 of the first example detectsa system voltage and outputs alternating current power having a voltagecorresponding to the system voltage. Hence, a plurality of kinds ofinverters corresponding to system voltages need not be prepared.

SECOND EXAMPLE

[0075]FIG. 5 is a block diagram showing the arrangement of a solar powergeneration apparatus of the second example. An inverter 107 of thesecond example has an output cable with a 200-V plug 311 attached to itsdistal end and an output cable having a 100-V plug 312 attached. Theplugs 311 and 312 can be connected to 200-V and 100-V wall sockets 314and 313 corresponding to the shapes of the plugs.

[0076]FIG. 6 is a block diagram showing the arrangement of atransforming circuit 105. Relays 204 and 205 forconnecting/disconnecting lines to be connected to the plugs 311 and 312are added to the arrangement of the transforming circuit 105 of thefirst example shown in FIG. 4. The contacts of the relays 204 and 205also serve as the switch 108 of the first example.

[0077] When detection values from voltage detectors 111 for detectingthe voltages of the lines of the plugs 311 and 312 are almost 0 V, acontrol circuit 104 turns off both the relays 204 and 205.

[0078] When the plug 311 is connected to the corresponding wall socket314, and a system voltage of 200 V is detected, the control circuit 104sends a signal to a relay 201 to connect two secondary windings of atransformer 203 in series and then sends a signal to the relay 204 toconnect the line for the plug 311 at an appropriate timing. As a result,the inverter 107 operates in an interconnected operation mode foroutputting alternating current power of 200 V.

[0079] On the other hand, when the plug 312 is connected to thecorresponding wall socket 313, and a system voltage of 100 V isdetected, the control circuit 104 sends a signal to the relay 201 toconnect two secondary windings of the transformer 203 in parallel andthen sends a signal to the relay 205 to connect the line for the plug312 at an appropriate timing. As a result, the inverter 107 operates inan interconnected operation mode for outputting alternating currentpower of 100 V.

[0080] When one of the relays 204 and 205 is being driven to connect theline, the control circuit 104 does not drive the other relay.

[0081] The control circuit 104 always monitors a current flowing to aline by a current detector 112. When the current flowing to the line hasa predetermined value or less, drive of the relay 204 or 205 isimmediately canceled to disconnect the line. This is because when theplug 311 or 312 is removed from the socket, an electrical shock accidentmay occur.

[0082] Alternatively, when the voltage detector 111 detects anabnormality of the line voltage, drive of the relay 204 or 205 iscanceled to disconnect the line. That is, in a system interconnectioninverter, a power outage detection function by a protecting unitdescribed in the “system interconnection technology operation guideline”acts, and the operation can be safely stopped.

[0083] The settling values and settling times are arbitrarily set inaccordance with the system to be connected to each line.

[0084] In addition, to prevent any short circuit when the plugs 311 and312 are simultaneously connected to the wall sockets or to prevent anyelectrical shock accident by an unconnected plug, the voltage detector111 and current detector 112 must be insulated from the main circuit.

[0085] When the plugs 311 and 312 are simultaneously connected to thewall sockets, the control circuit 104 preferentially sets the 200-Voutput. However, the 100-V output may be preferentially set.

[0086] Although not illustrated, the inverter 107 may have an outputsocket in the isolated operation mode. In this case, upon detectingpower outage, the control circuit 104 outputs a gate off signal to aboosting circuit 102 and inverter circuit 103 and cancels drive of therelay 204 or 205 to disconnect the inverter 107 from a system 110. Afterthat, the inverter circuit 103 is switched to the isolated operationmode and cancels the gate off signal. With this operation, alternatingcurrent power can be obtained from the output socket. Hence, even whenpower outage takes place due to disasters or the like, the solar powergeneration apparatus (at least the inverter 107) can be installed at anarbitrary position to supply the alternating current power to variousloads.

[0087] As described above, the inverter 107 of the second exampledetects a system voltage and outputs alternating current power having avoltage corresponding to the system voltage, as in the first example.Hence, a plurality of kinds of inverters corresponding to systemvoltages need not be prepared. In addition, the solar power generationapparatus can easily be connected to the system 110 through the plug 311or 312 to perform interconnected operation. In an emergency, the solarpower generation apparatus can be installed at an arbitrary position andused as an emergency power supply.

[0088] In the example shown in FIG. 5, the two plugs 311 and 312 areconnected. However, as in the first example, an output connector 106 maybe arranged at the output terminal of the inverter 107 such that only acable having a necessary plug at its distal end can be connected. Inthis arrangement, since the voltage and current need not be detected foreach of the lines connected to the two plugs 311 and 312, only a set ofsingle voltage detector 111 and current detector 112 suffices. Inaddition, one of the relays 204 and 205 of the transforming circuit 105can be omitted.

THIRD EXAMPLE

[0089] An inverter 107 of the third example has at its output terminalan output connector (receptacle) 801 for receiving a plug 802 as shownin FIG. 7. The shape of the plug 802 is discriminated as A, B, B3, BF,C, O, or SE. The plug 802 having a shape corresponding to the regionwhere the solar power generation apparatus is used or a voltage desiredby the user is used. The inverter 107 outputs a voltage corresponding tothe shape of the plug 802, and details will be described later.

[0090] The receptacle 801 has at its bottom portion an opening 808through which a projection 806 of the plug 802 can extend. Theprojection 806 extending through the opening 808 turns on a switch 807.When the switch 807 is ON, a control section 104 determines that theplug 802 for, e.g., 200 V is connected.

[0091] Electrodes 805 and 804 for power can fit each other. When theplug 802 is inserted into the receptacle 801, the inverter 107 isconnected to a system 110 through a cable 803.

[0092]FIG. 8 is a block diagram showing the arrangement of a solar powergeneration apparatus of the third example.

[0093] When the plug 802 connected to the receptacle 801 is for 100 V,the control circuit 104 controls the output voltage of a boostingcircuit 102 to the first target value (e.g., 160 V) and sets an invertercircuit 103 in an interconnected operation mode for 100-V output. Whenthe plug 802 is for 200 V, the control circuit 104 controls the outputvoltage of the boosting circuit 102 to the second target value (e.g.,320 V) and sets the inverter circuit 103 in an interconnected operationmode for 200-V output.

[0094] To change the voltage, the inductance of an inductor 5 shown inFIG. 1 or a system interconnection reactor (not shown) is changed asneeded, though a detailed description thereof will be omitted. Theoperation of a switch 108 is the same as in the first example. Althoughnot illustrated in FIG. 8, the solar power generation apparatus also hasa voltage detector or current detector. When the voltage indicated bythe plug 802 is different from the voltage of the system 110 or when aplug 312 is removed, the control circuit 104 turns off the switch 108.As in the first example, a transforming circuit 105 may be used tochange the voltage.

[0095] The inverter 107 shown in FIG. 8 also has a storage battery 617for supplying direct current power at night or when a solar batterymodule 101 cannot be connected, a charge/discharge control circuit 618for controlling charge and discharge of the storage battery 617, and aswitch 616 for making/breaking connection between the solar batterymodule 101 and the storage battery 617. The storage battery 617 can bearranged either in or outside the inverter 107. In the isolatedoperation mode, if the output of the solar battery module 101 is lessthan a predetermined voltage at night or due to weak sunlight, and adecrease in output of the solar battery module 101 is detected, thecontrol circuit 104 turns on the switch 616 to cause thecharge/discharge control circuit 618 to supply power from the storagebattery 617.

[0096] As described above, according to the inverter of the thirdexample, the system voltage can be known from the shape of the plugconnected to the inverter 107, and alternating current power having avoltage corresponding to the system voltage is outputted. Hence, aplurality of kinds of inverters corresponding to system voltages neednot be prepared. In addition, as in the second example, the solar powergeneration apparatus can easily be connected to the system 110 throughthe plug 311 or 312 to perform interconnected operation. Furthermore, inan emergency, the solar power generation apparatus can be installed atan arbitrary position together with the storage battery 617 andeffectively used as an emergency power supply.

[0097] When the solar power generation apparatus according to theabove-described first embodiment is used, the following effects can beexpected.

[0098] (1) Since the inverter of this embodiment detects the systemvoltage and outputs alternating current power with an appropriatevoltage, interconnected operation can easily be performed.

[0099] (2) Since the inverter of this embodiment outputs, e.g., 100-V or200-V alternating current power in correspondence with a system voltage,a plurality of inverters corresponding to system voltages to beconnected need not be manufactured and prepared.

[0100] (3) Since the inverter of this embodiment can be connected to asystem in a normal state or moved to an arbitrary position in anemergency, it can be effectively used as an emergency power supply.

[0101] (4) The inverter of this embodiment can easily be connected to awall socket in a building or the like without using any specialconnection and can also easily be connected to a system or supply powerin an emergency. In addition, even when the plug is removed from thewall socket or inappropriate connection is made, operation can beperformed in consideration of safety.

[0102] In the above description, system voltages of 100 V and 200 V havebeen exemplified. However, the solar power generation apparatus can becope with various system voltages in various regions.

[0103] When the solar power generation apparatus or inverter of thisembodiment is used as an emergency power supply, the output switch ofthe inverter is not turned on in some cases due to, e.g., the absence ofa system, though a detailed description thereof will be omitted. Inconsideration of this case, a switch for switching the operation of thecontrol circuit 104 to an emergency power supply operation mode ispreferably arranged. With this switch, an operation mode such as“normal”, “emergency 100-V output”, or “emergency 200-V output” can beset.

[0104] Normally, in consideration of, e.g., removal of the plug from thewall socket, when the output current value is a predetermined value orless, the output switch of the inverter is turned off. In an emergency,the output current value at which the output switch is turned off ismade smaller in consideration of a variation in load.

[0105] Second Embodiment

[0106] A solar power generation apparatus according to the secondembodiment of the present invention will be described below in detailwith reference to the accompanying drawings. The same reference numeralsas in the first embodiment denote the same parts in the secondembodiment, and a detailed description thereof will be omitted.

[0107] [Switch]

[0108] Switches of the second embodiment are formed from electromagneticswitches or breakers and inserted between the inverter and the firstoutput section, between the second output section and a branch pointbetween the inverter and the first output section, and in a panel boardbetween the first output section and a system. Of these switches, amechanical switch is turned off when the switch itself is OFF, andturned on when the switch itself is ON (or a reverse logic may be used).An electromagnetic switch is turned on/off upon receiving a signal froma control circuit 104.

[0109] [Plug Unit]

[0110] A plug unit 501 of the second embodiment has a function ofswitching from interconnected operation to isolated operation and/or afunction of determining an alternating current voltage to be outputtedfrom the output section of the inverter when inserted to the outputsection.

[0111] The plug unit 501 has an electrode receiving portion 502 having ashape connectable to the electrode of the output section, a projection503 for turning on an isolated operation start switch, and an electrodereceiving portion 504 (FIG. 14) capable of receiving the plug of a load,as shown in FIG. 13. The shape, number, and layout of projections can bechanged.

[0112] When the plug unit 501 is inserted into an output section 801 ofthe inverter, as shown in FIG. 14, the electrode receiving portion 502of the plug unit 501 is connected to an electrode 805 of the outputsection 801 of the inverter. The projection 503 projecting from the plugunit 501 turns on an isolated operation start switch 807 through a hole808 formed at the output section 801 so as to allow the inverter toexecute isolated operation.

[0113] After the electrodes are safely and surely connected, theprojection 503 turns on the isolated operation start switch 807. Withthis design, safety can be ensured because the inverter outputs novoltage until the plug unit 501 is completely inserted independently ofthe shape of the electrode of the output section 801 or the shape of theelectrode receiving portion 502.

[0114] A desired output voltage corresponding to the plug unit 501 canbe generated, and when the plug of a load to be operated is connected tothe electrode receiving portion 504 of the plug unit 501, the load canbe operated.

[0115] For the plug unit 501 and the output section 801 of the inverter,the shapes of the electrode and projection are not limited to thoseshown in FIGS. 13 and 14.

[0116] The shape of the electrode receiving portion is discriminated asA, B, B3, BF, C, O, or SE in accordance with a region where the inverteris used, a voltage desired by the user, or a load to be used. When theplug unit 501 having an electrode receiving portion with one of theabove shapes, the inverter outputs alternating current powercorresponding to that shape.

[0117] The plug unit 501 can have any shape such as a circular,triangular, or rectangular shape (FIG. 15). The outer shape can bechanged in accordance with the region where the inverter is used or thevoltage desired by the user. When the plug unit 501 having such a shapeis inserted, the inverter outputs alternating current powercorresponding to the outer shape.

[0118] For an AC module having an inverter attached to the lower surfaceof a solar battery module, if the inverter need be made compact, theinverter preferably has a single output section 801. In this case, asshown in FIG. 16, it is preferable to prepare in the single outputsection 801 a hole 808 and switch corresponding to the first targetoutput voltage and a hole 808 and switch corresponding to the secondtarget output voltage such that the single output section 801 can outputone of a plurality of different output voltages upon receiving a plugunit 501 corresponding to the output voltage.

FOURTH EXAMPLE

[0119]FIG. 9 is a block diagram showing the arrangement of a solar powergeneration apparatus of the fourth example. In the fourth example,interconnected operation is not performed, and power is supplied only toa load.

[0120] Referring to FIG. 9, reference numeral 101 denotes a directcurrent power supply; 102, a boosting circuit; 103, an inverter circuit;104, a control circuit; 405, a plug unit; 406, an output section; 107,an inverter; and 108, a switch.

[0121] Two solar battery modules PV-MR140 (140 W, 19.6 V, 7.15 A)available from Mitsubishi Electric are connected in series to constructa power supply for power of about 280 W with a rated output voltage of39.2 V and a current of 7.15 A. The numbers of series- andparallel-connected modules in the array are not particularly limited andare appropriately selected in accordance with the voltage of theinverter 107 and the current imputable range.

[0122] As shown in FIG. 15, the output section 406 has two outputsections for 100 V and 200 V.

[0123] When the solar power generation apparatus of the fourth exampleis connected to a load of 200 V, the plug unit 405 for 200 V is insertedinto the 200-V output section. Hence, as shown in Fig, 14, a projection503 of a plug unit 501 is inserted into a hole 808 of a 200-V outputsection 801, and an operation start switch (isolated operation startswitch) 807 is turned on through the hole 808.

[0124] The control circuit 104 sends a control signal corresponding tothe type of the plug unit 405 to control the output voltage of theboosting circuit 102 to the preset first target output voltage of 320 V.The control circuit 104 further sends a control signal to cause theinverter circuit 103 to output a voltage of 200 V so that alternatingcurrent power of about 200 V is outputted from the inverter 107.

[0125] When the solar power generation apparatus of the fourth exampleis connected to a load of 100 V, the plug unit 405 for 100 V is insertedinto the 100-V output section. Like the case of the 200-V load, and theoutput voltage of the boosting circuit 102 is controlled to the presetsecond target output voltage of 160 V. The inverter circuit 103 iscontrolled to output a voltage of 100 V so that alternating currentpower of about 100 V is outputted from the inverter 107.

[0126] As described above, when the plug unit 405 corresponding to thevoltage of a load to be connected is inserted into the output section406, a desired output voltage can be extracted from the inverter 107.The inverter 107 can be made compact and the desired output voltage caneasily be obtained without converting the output voltage using atransformer or the like.

FIFTH EXAMPLE

[0127]FIG. 10 is a block diagram showing the arrangement of a solarpower generation apparatus of the fifth example. The same referencenumerals as in the fourth example denote the same parts in the fifthexample, and a detailed description thereof will be omitted.

[0128] Referring to FIG. 10, reference numeral 407 denotes a firstoutput section; 410, a switch inserted between an inverter circuit 103and the first output section 407; and 411, a switch inserted between theinverter circuit 103 and a second output section 406.

[0129] As a direct current power supply 101, a power supply for power ofabout 5 kW with a rated output voltage of 235.2 V and a current of 21.45A is constructed using an array in which 12×3 solar battery modulesPV-MR140 described above are connected in series and parallel. Thenumbers of series- and parallel-connected modules in the array are notparticularly limited and are appropriately selected in accordance withthe voltage of an inverter 107 and the current inputtable range.

[0130] The first output section 407 of the solar power generationapparatus of the fifth example is connected to a single-phase three-wire200-V system 110. In accordance with a control signal from a controlcircuit 104, a boosting circuit 102 operates such that its outputvoltage becomes the preset first target output voltage of 320 V. Inaccordance with a control signal from the control circuit 104, theinverter circuit is controlled to output a voltage of 200 V. Alternatingcurrent power of about 200 V is outputted from the inverter 107 andsupplied to the load or system 110.

[0131] When a power outage detector (not shown) detects power outage onthe basis of the output of the inverter 107 or a current flowing to thesystem 110, the control circuit 104 outputs a gate off signal to theboosting circuit 102 and inverter circuit 103 and also turns off theswitch 410 to disconnect the inverter 107 from the system 110.

[0132] To make the inverter 107 execute isolated operation at the timeof power outage, a plug unit 405 is inserted into the second outputsection 406. Upon receiving a signal representing insertion of the plugunit 405, the control circuit 104 switches the inverter 107 to theisolated operation mode. That is, the control circuit 104 turns on theswitch 411 to connect the second output section 406 and inverter circuit103. In this case, the switch 411 may be a switch that can be manuallyturned on.

[0133] When the plug unit 405 for 100 V is inserted into the secondoutput section 406, the control circuit 104 performs control such thatthe output voltage of the boosting circuit 102 becomes the preset secondtarget output voltage of 160 V, and the inverter circuit 103 outputs avoltage of 100 V. Alternating current power of about 100 V is outputtedfrom the second output section 406 of the inverter 107.

[0134] If isolated output is necessary due to a reason other than poweroutage, the plug unit 405 for a desired voltage is inserted into thesecond output section 406. The inverter 107 is switched to the isolatedoperation mode, and a desired voltage corresponding to the load to beused can be obtained.

[0135] As described above, when the plug unit 405 is inserted into thesecond output section 406, a desired output voltage can be extractedfrom the inverter 107. The inverter 107 can be made compact and thedesired output voltage can easily be obtained without converting theoutput voltage using a transformer or the like.

SIXTH EXAMPLE

[0136]FIG. 11 is a block diagram showing the arrangement of a solarpower generation apparatus of the sixth example. The same referencenumerals as in the fourth or fifth example denote the same parts in thesixth example, and a detailed description thereof will be omitted.

[0137] As a direct current power supply 101, the same arrangement as inthe fourth example is used, though the present invention is not limitedto this. In the sixth example, a storage battery 617 is arranged outsidean inverter 107, though it may be incorporated in the inverter 107.

[0138] As in the fifth example, a control circuit 104 controls aboosting circuit 102 and inverter circuit 103 in accordance with a plugunit 405 inserted into a second output section 406.

[0139] If the output voltage of the direct current power supply 101 doesnot exceed a predetermined value, the control circuit 104 detects adecrease in output of the direct current power supply 101, turns on aswitch 616, and sends a signal to a charge/discharge control circuit 618such that power stored in the storage battery 617 can be used.

[0140] The same effects as in the fifth example can be expected. Inaddition, since both the direct current power supply 101 and storagebattery 617 are used, the solar power generation apparatus can be moreeffectively used as an emergency power supply.

SEVENTH EXAMPLE

[0141]FIG. 12 is a view showing the outer appearance of an AC moduleusing an inverter of the seventh example.

[0142] Referring to FIG. 12, reference numeral 401 denotes a solarbattery module; 402, an inverter; and 403, an output cable.

[0143] A module that is the same as in the fourth example is used as thesolar battery module 401. However, the present invention is not limitedto this.

[0144] The output cable 403 of the AC module is connected to the neutralline and one power line of the lines of a single-phase three-wire 200-Vsystem. The internal control circuit executes control such that theoutput voltage of the internal boosting circuit becomes the presentfirst target output voltage of 160 V, and the internal inverter circuitoutputs a voltage of 100 V. Hence, alternating current power of about100 V can be obtained from the inverter 402.

[0145] If power outage occurs due to an earthquake or the like and isdetected on the basis of the output of the inverter 402 or the currentflowing between the system and the AC module, the inverter 402 andsystem are electrically disconnected. In this case, the AC module iscaused to execute isolated operation described in the fifth and sixthexamples at that position or at a remote position such as a place ofrefuge, thereby supplying alternating current power to a load.

[0146] As described above, when a plug unit 405 is switched inaccordance with a load, alternating current power with a desired voltagecan be extracted from the AC module. Hence, the same effects as in thefifth and sixth examples can be expected, and the AC module can beeffectively used as an emergency power supply.

[0147] According to the above-described second embodiment, the followingeffects can be expected.

[0148] (1) A desired output voltage can easily be extracted by switchingmeans.

[0149] (2) The output voltage need not be converted using a transformeror the like, and the inverter can be made compact.

[0150] (3) When a plug unit corresponding to a load is inserted into theinverter, a desired voltage can easily be extracted.

[0151] (4) Especially, when the inverter of this embodiment is used foran AC module, it can be effectively used as an emergency power supply.

[0152] As many apparently widely different embodiments of the presentinvention can be made without departing from the spirit and scopethereof, it is to be understood that the invention is not limited to thespecific embodiments thereof except as defined in the appended claims.

What is claimed is:
 1. A power converting apparatus which is connectedto an electric power system, said apparatus comprising: a convertingcircuit, arranged to convert direct current power to alternating currentpower; a transforming circuit, arranged to transform voltage outputtedfrom said converting circuit; a switch, arranged to make/breakconnection between said transforming circuit and the electric powersystem; and a controller, arranged to control operation of saidconverting circuit and transforming circuit, and connection of saidswitch based on a line voltage of the electric power system and/or aconnection state between said apparatus and the electric power system.2. The apparatus according to claim 1, further comprising a detector,arranged to detect the line voltage, wherein said controller controlsthe output voltage of said converting circuit in accordance with thedetected line voltage.
 3. The apparatus according to claim 1, furthercomprising a detector, arranged to detect the line voltage, wherein saidcontroller controls transformation ratio of said transforming circuit inaccordance with the detected line voltage.
 4. The apparatus according toclaim 1, further comprising: a detector, arranged to detect the linevoltage; and plural connectors, each of which is arranged to connectbetween said switch and the electric power system, wherein saidcontroller activates one of said plural connectors based on the linevoltage detected by said detector.
 5. The apparatus according to claim1, further comprising: a detector, arranged to detect the line voltage;and a booster circuit, arranged to boost voltage of the direct currentpower to be inputted to said converting circuit, wherein said controllercontrols the voltage outputted by said booster circuit.
 6. A powerconverting apparatus which is connected to an electric power system,said apparatus comprising: a converting circuit, arranged to convertdirect current power to alternating current power; a transformingcircuit, arranged to transform voltage outputted from said convertingcircuit; a switch, arranged to make/break connection between saidtransforming circuit and the electric power system; and a controller,arranged to control operation of said converting circuit and/ortransforming circuit, and control connection of said switch based on atype of connector which is used to connection between said apparatus andthe electric power system.
 7. The apparatus according to claim 6,wherein said controller discriminates the type of connector, andcontrols voltage outputted from said converting circuit based on thediscriminated type of connector.
 8. The apparatus according to claim 6,further comprising a booster circuit, arranged to boost voltage of thedirect current power to be inputted to said converting circuit, whereinsaid controller discriminates the type of connector, and controlsvoltage outputted from said booster circuit based on the discriminatedtype of connector.
 9. The apparatus according to claim 6, wherein saidcontroller discriminates the type of connector, and sets transformationratio of said transforming circuit based on the discriminated type ofconnector.
 10. A power converting apparatus which is connected to anelectric power system, said apparatus comprising: a converting circuit,arranged to convert direct current power to alternating current power; aswitch, arranged to make/break connection between said convertingcircuit and the electric power system; and a controller, arranged tocontrol operation of said converting circuit and connection of switchbased on a type of connector which is used to connection between saidapparatus and the electric power system.
 11. The apparatus according toclaim 10, wherein said controller discriminates the type of connector,and controls voltage outputted from said converting circuit based on thediscriminated type of connector.
 12. The apparatus according to claim10, further comprising a booster circuit, arranged to boost voltage ofthe direct current power to be inputted to said converting circuit,wherein said controller discriminates the type of connector, andcontrols voltage outputted from said booster circuit based on thediscriminated type of connector.
 13. A power generating apparatus forgenerating electric power, comprising the power converting apparatusaccording to claim
 1. 14. The apparatus according to claim 13, furthercomprising a solar battery.
 15. The apparatus according to claim 13,further comprising a charge/discharge controller for a storage battery.16. A power generating apparatus for generating electric power,comprising the power converting apparatus according to claim
 6. 17. Theapparatus according to claim 16, further comprising a solar battery. 18.The apparatus according to claim 16, further comprising acharge/discharge controller for a storage battery.
 19. A powergenerating apparatus for generating electric power, comprising the powerconverting apparatus according to claim
 10. 20. The apparatus accordingto claim 19, further comprising a solar battery.
 21. The apparatusaccording to claim 19, further comprising a charge/discharge controllerfor a storage battery.
 22. A power converting apparatus for convertingelectric power comprising: a booster circuit, arranged to boost voltageof direct current power inputted from a direct current power supply; aninverter circuit, arranged to convert the direct current power, which isinputted from said booster circuit, to alternating current power; anoutput port, arranged to output the alternating power supplied from saidinverter circuit; and a controller, arranged to control operation ofsaid booster and inverter circuits based on a type of plug unitconnected to said output port.
 23. The apparatus according to claim 22,wherein said controller controls said booster and inverter circuits sothat said apparatus outputs a voltage corresponding to the type of plugunit which is connected to said output port by a user.
 24. The apparatusaccording to claim 23, wherein the plug unit has electrodes and at leastone of projection which operates a switch arranged to said output ports.25. The apparatus according to claim 24, wherein said controllercontrols said booster and inverter circuits in accordance with theoperation of the switch.
 26. A power converting apparatus for convertingelectric power comprising: a booster circuit, arranged to boost voltageof direct current power inputted from a direct current power supply; aninverter circuit, arranged to convert the direct current power, which isinputted from said booster circuit, to alternating current power; afirst output port, arranged to output the alternating power suppliedfrom said inverter circuit through a first switch; a second output port,arranged to output the alternating power supplied from said invertercircuit through a second switch; and a controller, arranged to controloperation of said booster and inverter circuits, wherein said controllermakes the first switch and breaks the second switch when said apparatusis operated and connected to an electric power system, and breaks thefirst switch and makes the second switch when said apparatus is operatedand no connected to the electric power system, and said controllercontrols the operation of said booster and inverter circuits based on aconnection state of said first or second output port.
 27. The apparatusaccording to claim 26, wherein, if said apparatus is connected to theelectric power system and a plug unit is connected to said second outputport, said controller disconnects said apparatus from the electric powersystem.
 28. The apparatus according to claim 26, wherein said controllercontrols the operation of said booster and inverter circuits so thatsaid apparatus outputs a voltage corresponding to a plug unit which isconnected to said first or second output port by a user.
 29. Theapparatus according to claim 28, wherein the plug unit has electrodesand at least one of projection which operates a third switch arranged tosaid first output port or a fourth switch arranged to said second outputport.
 30. The apparatus according to claim 29, wherein said controllercontrols the operation of said booster and inverter circuits inaccordance with states of the third and fourth switches.
 31. Theapparatus according to claim 26, further comprising a fifth switch, acharge/discharge controller and a storage battery between the directcurrent power supply and said booster circuit.
 32. A power generatingapparatus for generating electric power, comprising a solar battery andthe power converting apparatus according to claim
 22. 33. A powergenerating system comprising a plurality of the power generatingapparatuses according to claim
 32. 34. A power generating apparatus forgenerating electric power, comprising a solar battery and the powerconverting apparatus according to claim
 26. 35. A power generatingsystem comprising a plurality of the power generating apparatusesaccording to claim
 34. 36. A control method of a power convertingapparatus, which is connected to an electric power system, havingconverting circuit arranged to convert direct current power toalternating current power, a transforming circuit arranged to transformvoltage outputted from the converting circuit, and a switch arranged tomake/break connection between the transforming circuit and the electricpower system, comprising the steps of: discriminating a line voltage ofthe electric power system and/or a connection state between theconverting apparatus and the electric power system; and controllingoperation of the converting circuit and transforming circuit, andconnection of the switch based on the discriminated line voltage and/orconnection state.
 37. A control method of a power converting apparatus,which is connected to an electric power system, having a convertingcircuit arranged to convert direct current power to alternating currentpower, a transforming circuit arranged to transform voltage outputtedfrom the converting circuit and a switch arranged to make/breakconnection between the transforming circuit and the electric powersystem, comprising the steps of: discriminating a type of connectorwhich is used to connection between the power converting apparatus andthe electric power system; and controlling operation of the convertingcircuit and/or transforming circuit, and controlling connection of theswitch, based on the discriminated type of connector.
 38. A controllingmethod of a power converting apparatus, which is connected to anelectric power system, having a converting circuit arranged to convertdirect current power to alternating current power and a switch arrangedto make/break connection between the converting circuit and the electricpower system, comprising the steps of: discriminating a type ofconnector which is used to connection between the power convertingapparatus and the electric power system; and controlling operation ofthe converting circuit and connection of the switch based ondiscriminated type of connector.
 39. A controlling method of a powerconverting apparatus for converting electric power having a boostercircuit arranged to boost voltage of direct current power inputted froma direct current power supply, an inverter circuit arranged to thedirect current power, which is inputted from the booster circuit, toalternating current power and an output port arranged to output thealternating power supplied from the inverter circuit, comprising thestep of controlling operation of the booster and inverter circuits basedon a type of plug unit connected to the output port.
 40. A controllingmethod of a power converting apparatus for converting electric powerhaving a booster circuit arranged to boost voltage of direct currentpower inputted from a direct current power supply, an inverter circuitarranged to the direct current power, which is inputted from the boostercircuit, to alternating current power, a first output port arranged tooutput the alternating power supplied from the inverter circuit througha first switch and a second output port, arranged to output thealternating power supplied from the inverter circuit through a secondswitch, comprising the steps of: discriminating an operation state ofthe power converting apparatus and a connection state between the firstor second output port and an electric power system; making and/orbreaking the first and second switches in accordance with thediscriminated operation and connection states; and controlling operationof the booster and inverter circuits in accordance with thediscriminated operation and connection states.